The most beloved song of country star Tim McGraw’s career is probably still 2004’s “Live Like You Were Dying,” a ballad about a man whose side effects from a cancer scare include taking up both emotional and physical pursuits: “I went skydiving / I went Rocky Mountain climbing,” goes part of the chorus. So you can see why McGraw might have related to “Free Solo,” the documentary about Alex Harrold: It’s practically “Live Like You Were Dying: The Motion Picture.” Except the threat of dying comes from climbing El Capitan.

McGraw said he was too busy to consider working on a theme song when the request came in, since earlier this year he was juggling another Soul 2 Soul tour with spouse Faith Hill and a solo album that’s still in the works for 2019. Then he watched a screener with his daughters while they were all at home on a break, and he was taken enough with it to take up the offer and co-write “Gravity.” “It is scary, the movie — I mean, it’s like a roller coaster ride. You’re on the edge of your seat the whole time.” But it won’t personally inspire him to live like he was dying. “I would never do that in a million years,” says the singer. “I’m afraid of heights. Although, after 400 or 500 feet, it’s all relative anyway, on the way up.”

He shared writing duties with friend Lori McKenna, the acclaimed Americana songwriter who wrote his recent hit “Humble and Kind,” which marked a definitive turning point in country from the bro movement back toward something… humbler and kinder. She channeled their phone conversations into a finished song. The central line, “Gravity is a fragile thing,” seems ambiguous in an otherwise uplifting song. He says it has to do with a metaphorical fear of falling. “For me, it means that if you don’t go after your job and what you do with joy and intent and purpose — or, as a sports analogy, if you’re just going through the patterns when you run that play — you’ll f— it up eventually, and fall away from what your true north is.”

McGraw is an infrequent songwriter but has a thing for the kind of assignment writing a film offers. “You want to lend an ear to what the viewer is seeing, but you also want to write something that independently can stand on its own and give you a good message,” he says. “So I think there’s a cool challenge when you’re writing something for a film to not be on the nose, but be somewhere on the face, I guess.”